Moreover, defective autophagy, leading to endoplasmic reticulum stress in astrocytes, has been recognized as an early event in organoid slice cultures generated from patients harboring hexanucleotide repeat expansions in the C9orf72 gene, which is also implicated in the pathogenesis of ALS and FTD [100]. Here, C9orf72 is linked to amyotrophic lateral sclerosis.